The series is set 97 years after a devastating nuclear war that wiped out all life on Earth. The only survivors were supposed to be the residents of twelve space stations in Earth orbit prior to the war, and a handful of "grounders" who managed to escape to the space stations. These space stations banded together to form a single massive station named "The Ark", where about 2,400 people live.[1] Resources are scarce and all crimes no matter their nature or severity are punishable by death ("floating") unless the perpetrator is under 18 years of age. After the Ark's life support systems are found to be critically failing, one hundred imprisoned convicts are declared "expendable" and sent to the surface in a last ditch attempt to determine if Earth is habitable again.